The question is good, and the answer is subject. Some subjects have more meaning. Now look; I have seen a room full of impressionistic paintings of hay stacks looking like muffins, and the question comes to mind, of, in what sense are they art? You have to understand the circumstances. First, photography was coming into its own, though without color, and always with direct light upon it. If the artist chose a common enough subject in the hay stacks, that was light, shadow, and color that was the subject. Art is always the same, but no one wants the same from art. Rather, a part of the challenge is to present the art in a new fashion, but also, as always to find meaningful subjects for art. That artist who sees as meaningful what all people see as meaningful has his task half done. Then it becomes only a question execution, or skill, or ability.

I read the whole text but i dont understand to well the last question.

#40. But how are we to define good and bad art with reference to its subject matter?

For two blinde men that have never seen 3D things in theire entire life.
The 3D things are the truth.

I would Agreed with that & I think anti-art movements prove this as well an example would be Marcel Duchamp piece the fountain

Life is art, and the good life is fine art. Death is only life's version of nothing; nothing to do, nothing to say, no one to pay, and nothing to play. Ask them bones what's in theys heads, and nothings the answer becauses they's dead. We give death meaning from the haunted house of the living. Booo!

I've always thought that art is anything which inspires beauty...
Just anything you stop to look at and think, wow
That can be something natural, like a sunset, or the Mona Lisa, whatever, if it makes you stop and stare, and gives you those shivers down your spine, its art.

A little crude, but that's my personal opinion.

And then there's art as an institution. Here, its difficult to say. There's a very thin line which has become more and more blurred. To begin with, art was the only way of representing reality, it had a purpose. Then you get the camera and some big changes start to happen. Art doesn't need to represent reality anymore, you have pictures for that, it needs to serve some other purpose, maybe to make you think or feel, take Picasso and the cubists. Then you get Warhol et al, and art is suddenly about the celebrity - 'Everything the artist spits is art' - Duchamp.
And it just goes downhill from there...
In fact, as soon as art no longer had a purpose, it was a downhill slope to where we are today, nowadays who even knows what art is? We know only what we're told, and we're told it by people who accept anything they don't understand as art - both for fear of looking stupid and for the masses of money they're going to make.

You want to know what art is - well to be honest, its an institution, nothing more.

Art is what people do, and not nature...In the middle ages philosophers reflected the thought that all useful activities were art... This has changed since people have become alienated from the means of production...If what you do resembles the work of slaves, it cannot be art, because slaves have technicallybecome beasts, and parts of nature..

Well I suppose your defining art as purely a human creation, i.e. as being created with the intention of inspiring beauty.
But humans are the only creatures capable of seeing beauty, they simply project the quality of being beautiful onto an image which does not possess that quality innately.

So surely, a sunset can be, and is, as beautiful as a human produced work of art, because what makes both of them beautiful is not the way in which they were created, but the fact that they are being viewed by someone who personally sees some beauty in them.